Percent body fat measuring apparatus using a half-wave waveform

Abstract

A percent body fat measuring apparatus includes a first and a second electrodes with which a living body is brought into contact, a detection resistor of which one terminal is connected to the second electrode, signal generator which produces a measurement signal and applies a produced measurement signal between the first electrode and the other terminal of the detection resistor, level detector for detecting the level of a signal which develops between the terminals of the detection resistor and is an object of detection, and percent body fat computer for determining percent body fat on the basis of a result of detection operation performed by the level detector. A measurement signal produced by the signal generator is made analogous to a half-wave waveform, and the level detector detects the level of a waveform analogous to a half-wave of the signal to be detected.

1. A percent body fat measuring apparatus comprising:
 first and second electrodes with which a living body is brought into contact; 
 a detection resistor of which one terminal is connected to the second electrode; 
 a signal generator which produces a measurement signal and applies a produced measurement signal between the first electrode and the other terminal of the detection resistor; 
 a level detector for detecting the level of a signal which develops between the terminals of the detection resistor and is an object of detection; and 
 a percent body fat computer for determining percent body fat on the basis of a result of detection operation performed by the level detector, 
 wherein a measurement signal produced by the signal generator is analogous to a half-wave waveform; 
 wherein the level detector detects the level of a waveform analogous to a half-wave of the signal to be detected; 
 wherein the signal generator includes;
 a pulse generator for generating a pulse signal indicating the cycle of the measurement signal, 
 a first resistor of which one terminal is connected to an output terminal of the pulse generator, 
 a second resistor of which one terminal is connected to the other terminal of the first resistor, 
 a first p-n-p transistor of which base is connected to the other terminal of the second resistor, of which collector is grounded, and of which emitter is connected to a positive power supply via a third resistor, 
 a first capacitor of which one terminal is connected to a node between the first and the second resistors and of which other terminal is connected to the emitter of the first p-n-p transistor, and 
 a second capacitor connected between a base of the first p-n-p transistor and a ground level; 
 
 wherein the level detector includes:
 a third capacitor of which one terminal is connected to the second electrode, 
 a second p-n-p transistor of which base is connected to the other terminal of the third capacitor, of which collector is grounded via a fourth resistor, and of which emitter is connected to the positive power supply via a fifth resistor, 
 a bias circuit for supplying a bias current to the base of the second p-n-p transistor, and 
 a rectifier circuit for rectifying an output from the collector of the second p-n-p transistor; 
 
 wherein the pulse generator includes:
 an original pulse generator which is formed from a microcomputer and produces the original pulse signal indicating the cycle of the measurement signal, 
 a sixth resistor of which one terminal is connected to the positive power supply, and 
 a switching element of which one terminal is connected to the other terminal of the sixth resistor, of which other terminal is grounded, and of which connection is controlled by an original pulse signal; 
 wherein a node between the sixth resistor and the switching element is a terminal for outputting the pulse signal. 
 
 
   
   
     2. A percent body fat measuring apparatus comprising:
 first and second electrodes with which a living body is brought into contact; 
 a detection resistor of which one terminal is connected to the second electrode; 
 a signal generator which produces a measurement signal and applies a produced measurement signal between the first electrode and the other terminal of the detection resistor; 
 a level detector for detecting the level of a signal which develops between the terminals of the detection resistor and is an object of detection; and 
 a percent body fat computer for determining percent body fat on the basis of a result of detection operation performed by the level detector, 
 wherein a measurement signal produced by the signal generator is analogous to a half-wave waveform; and 
 wherein the level detector detects the level of a waveform analogous to a half-wave of the signal to be detected; 
 wherein the signal generator includes:
 a pulse generator for generating a pulse signal indicating the cycle of the measurement signal, 
 a first resistor of which one terminal is connected to an output terminal of the pulse generator, 
 a second resistor of which one terminal is connected to the other terminal of the first resistor, 
 a first p-n-p transistor of which base is connected to the other terminal of the second resistor, of which collector is grounded, and of which emitter is connected to a positive power supply via a third resistor, 
 a first capacitor of which one terminal is connected to a node between the first and second resistors and of which other terminal is connected to the emitter of the first p-n-p transistor, and 
 a second capacitor connected between the base of the first p-n-p transistor and a ground level. 
 
 
   
   
     3. The percent body fat measuring apparatus according to  claim 2 , wherein the level detector includes:
 a third capacitor of which one terminal is connected to the second electrode, 
 a second p-n-p transistor of which base is connected to the other tenninal of the third capacitor, of which collector is grounded via a fourth resistor, and of which emitter is connected to the positive power supply via a fifth resistor, 
 a bias circuit for supplying a bias current to the base of the second p-n-p transistor, and 
 a rectifier circuit for rectifying an output from the collector of the second p-n-p transistor. 
 
   
   
     4. A percent body fat measuring apparatus comprising:
 first and second electrodes with which a living body is brought into contact; 
 a detection resistor of which one terminal is connected to the second electrode; 
 a signal generator which produces a measurement signal and applies a produced measurement signal between the first electrode and the other terminal of the detection resistor; 
 a level detector for detecting the level of a signal which develops between the terminals of the detection resistor and is an object of detection; and 
 a percent body fat computer for determining percent body fat on the basis of a result of detection operation performed by the level detector, 
 wherein a measurement signal produced by the signal generator is analogous to a half-wave waveform; and 
 wherein the level detector detects the level of a waveform analogous to a half-wave of the signal to be detected; 
 wherein the signal generator includes:
 a pulse generator for generating a pulse signal indicating the cycle of the measurement signal, 
 a first resistor of which one terminal is connected to an output terminal of the pulse generator, 
 a second resistor of which one terminal is connected to the other terminal of the first resistor, 
 a first n-p-n transistor of which base is connected to the other terminal of the second resistor, of which collector is connected to a positive power supply, and of which emitter is grounded via a third resistor, 
 a first capacitor of which one terminal is connected to a node between the first and second resistors and of which other terminal is connected to an emitter of the first n-p-n transistor, and 
 a second capacitor connected between a base of the first n-p-n transistor and a ground level. 
 
 
   
   
     5. The percent body fat measuring apparatus according to  claim 4 , wherein the level detector includes:
 a third capacitor of which one terminal is connected to the second electrode, 
 a second n-p-n transistor of which base is connected to the other terminal of the third capacitor, of which collector is connected to the positive power supply via a fourth resistor, and of which emitter is grounded via a fifth resistor, 
 a bias circuit for supplying a bias current to the base of the second n-p-n transistor, and 
 a rectifier circuit for rectifying an output from the collector of the second n-p-n transistor. 
 
   
   
     6. The percent body fat measuring apparatus according to  claim 4 , wherein the pulse generator includes:
 an original pulse generator which is formed from a microcomputer and produces an original pulse signal indicating the cycle of the measurement signal, 
 a sixth resistor of which one terminal is connected to the positive power supply, and 
 a switching element of which one terminal is connected to the other terminal of the sixth resistor, of which other terminal is grounded, and of which connection is controlled by an original pulse signal, 
 wherein a node between the sixth resistor and the switching element is a terminal for outputting the pulse signal. 
 
   
   
     7. A percent body fat measuring apparatus comprising:
 first and second electrodes, with which a living body is brought into contact; 
 a detection resistor, of which a first terminal is connected to the second electrode; 
 a signal generator which produces a measurement signal in a form of a waveform that is analogous to a half-wave waveform and applies a produced measurement signal between the first electrode and a second terminal of the detection resistor; 
 a level dctcctor. which detects the levcl of a waveform analogous to a half-wave of a signal developing between the terminals of the detection resistor and outputs a result of detection as a detection signal; 
 a percent body fat computer for determining percent body fat on the basis of a level of the detection signal, 
 the level detector including:
 a connection capacitor, of which a first terminal is connected to the second electrode, 
 a p-n-p transistor, of which a base is connected to a second terminal of the connection capacitor, of which a collector is grounded via a first resistor, and of which an emitter is connected to a positive power supply via a second resistor, 
 a bias circuit for supplying a bias current to the base of the p-n-p transistor, and 
 a rectifier circuit which rectifies an output from the collector of the p-n-p transistor and outputs a rectified output as the detection signal; and 
 
 a corrector for subtracting a correction level value of the detection signal from an output level value of the detection signal, 
 wherein the correction level value is equivalent to a level value of the detection signal obtained by imparting an additional bias current to the p-n-p transistor while generation of the measurement signal is suspended, 
 wherein the output level value is equivalent to an output from the rectifier circuit when the living body comes into contact with the first and second electrodes while a measurement signal is produced; 
 wherein the percent body fat computer determines percent body fat based on a result of correction performed by the corrector. 
 
   
   
     8. A percent body fat measuring apparatus comprising:
 first and second electrodes, with which a living body is brought into contact; 
 a detection resistor, of which a first terminal is connected to the second electrode; 
 a signal generator which produces a measurement signal whose waveform is analogous to a half-wave waveform and applies a produced measurement signal between the first electrode and a second terminal of the detection resistor; 
 a level detector which detects the level of a waveform analogous to a half-wave of a signal developing between the terminals of the detection resistor and outputs a result of detection as a detection signal; and 
 a percent body fat computer for determining percent body fat on the basis of a level value of the detection signal; 
 the level detector including:
 a connection capacitor, of which a first terminal is connected to the second electrode, 
 a p-n-p transistor, of which a base is connected to a second terminal of the connection capacitor, of which a collector is grounded via a first resistor, and of which an emitter is connected to a positive power supply via a second resistor, 
 a bias circuit for supplying a bias current to the base of the p-n-p transistor, and 
 a rectifier circuit which rectifies an output from the collector of the p-n-p transistor and outputs a rectified output as the detection signal; 
 
 a corrector for correcting an output level value of the detection signal with a correction level value, 
 wherein the output level value is output from the rectifier circuit when a living body comes into contact with the first and second electrodes while a measurement signal is produced, and 
 wherein the correction level value is equivalent to a level value of the detection signal obtained by imparting an additional bias current to the p-n-p transistor while generation of the measurement signal is suspended, 
 wherein the percent body fat computation determines percent body fat based on a result of correction performed by the corrector. 
 
   
   
     9. A percent body fat measuring apparatus comprising:
 first and second electrodes, with which a living body is brought into contact; 
 a detection resistor, of which a first terminal is connected to the second electrode; 
 a signal generator which produces a measurement signal in a form of a waveform that is analogous to a half-wave waveform and applies a produced measurement signal between the first electrode and a second terminal of the detection resistor; 
 a level detector which detects the level of a waveform analogous to a half-wave of a signal developing between the terminals of the detection resistor and outputs a result of detection as a detection signal; and 
 a percent body fat computer for determining percent body fat on the basis of a level value of the detection signal; 
 the level detector including:
 a connection capacitor, of which a first terminal is connected to the second electrode, 
 an n-p-n transistor, of which a base is connected to a second terminal of the connection capacitor, of which a collector is connected to a positive power supply via a first resistor, and of which an emitter is grounded via a second resistor, 
 a bias circuit for supplying a bias current to the base of the n-p-n transistor, and 
 a rectifier circuit which rectifies an output from the collector of the n-p-n transistor; 
 
 a corrector for subtracting a correction level value of the detection signal from an output level value of the detection signal, 
 wherein the correction level value is equivalent to a level value of the detection signal obtained by imparting an additional bias current to the n-p-n transistor while generation of the measurement signal is suspended, 
 wherein the output level value is equivalent to an output from the rectifier circuit when the living body comes into contact with the first and second electrodes while a measurement signal is produced; 
 wherein the percent body fat computer determines percent body fat based on a result of correction performed by the corrector. 
 
   
   
     10. A percent body fat measuring apparatus comprising:
 first and second electrodes, with which a living body is brought into contact; 
 a detection resistor, of which a first terminal is connected to the second electrode; 
 a signal generator which produces a measurement signal of which waveform is analogous to a half-wave waveform and applies a produced measurement signal between the first electrode and a second terminal of the detection resistor; 
 a level detector which detects the level of a waveform analogous to a half-wave of a signal developing between the terminals of the detection resistor and outputs a result of detection as a detection signal; and 
 a percent body fat computer for determining percent body fat on the basis of a level value of the detection signal; 
 the level detector including:
 a connection capacitor, of which a first terminal is connected to the second electrode, 
 an n-p-n transistor, of which a base is connected to a second terminal of the connection capacitor, of which a collector is connected to a positive power supply via a first resistor, and of which an emitter is grounded via a second resistor, 
 a bias circuit for supplying a bias current to the base of the n-p-n transistor, and 
 a rectifier circuit which rectifies an output from the collector of the n-p-n transistor; 
 
 a corrector for correcting an output level value of the detection signal with a correction level value, 
 wherein the output level value is output from the rectifier circuit when a living body comes into contact with the first and second electrodes while a measurement signal is produced, and 
 wherein the correction level value is equivalent to a level value of the detection signal obtained by imparting an additional bias current to the n-p-n transistor while generation of the measurement signal is suspended, 
 wherein the percent body fat computer determines percent body fat based on a result of correction performed by the corrector.